docs: def publishing_prepare_published_copy(self, draft_obj):
          """ Prepare published copy of draft prior to saving it """
          # We call super here, somewhat perversely, to ensure this method will
          # be called on publishable subclasses if implemented there.
          mysuper = super(PublishingModel, self)
          if hasattr(mysuper, 'publishing_prepare_published_copy'):
              mysuper.publishing_prepare_published_copy(draft_obj)